In addition to frequent somatic mutations in RHOA [11, 31, 36, 37] and epigenetic modifiers, several studies have shown frequent alterations affecting TCR signaling-related genes, including CD28 [38, 39], FYN [36, 39], PLCγ1 [39] and VAV1 [39] in cutaneous T-cell lymphomas, AITL and adult T cell leukemia/lymphoma. The gene discussed is FYN; the disease is primary cutaneous T-cell non-Hodgkin lymphoma.